Geir Mogen, NTNU

By using tiny biological light switches, scientists have identified the network of cells that fire as rats navigate a maze for treats.

By Tia Ghose, LiveScience

Scientists have watched a specific network of brain cells light up in rats to create a mental map of their location.

The new study, in which researchers looked at brain cells that literally turned on and off like light switches as rats navigated a maze, could shed light on how the brain creates a sense of place.

The study is published Thursday in the journal Science.

Finding our place
Scientists have known the hippocampus is involved in creating mental maps, but less certain is exactly how mental maps form or why we get lost. Past studies showed that specific place cells in the hippocampus fired when animals explored a new space, but knowing which brain cells sent information to the place cells proved trickier.

That's because tracing how any number of unknown brain cells, or neurons, are hooked up can be incredibly complicated — even in relatively simple animals such as rats.

"A rat's brain is the size of a grape. Inside there are about 50 million neurons that are connected together at a staggering 450 billion places," said study co-author Edvard Moser, director of the Kavli Institute, in a statement.

Mental maps
To watch the entire process of learning a new place unfold, Moser and his colleagues created a virus that could insert tiny biological light switches into the neurons of rats. Next, they threaded optical fiber into the rats' brains to connect to the light-switch-enhanced brain cells, allowing the researchers to turn the lights on and activate the neurons at will. Finally, they inserted electrodes that could record electrical signals traveling between different brain cells.

The team flipped those biological light switches on and off about 10,000 times as rats navigated a maze seeking tasty treats, which enabled the scientists to identify individual neurons. Simultaneously, they measured the electrical signals traveling between these brain cells.

By combining the two pieces of information, the team was able to recreate the neural network that fires as the animals learned their location. It turned out that many different cell types were involved in creating a sense of place.

The findings raise questions about cells that have not previously been tied to orientation.

"One mystery is the role that the cells that are not part of the sense of direction play. They send signals to place cells, but what do they actually do?" Moser said in a statement.

Follow Tia Ghose on Twitter @tiaghose. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.com.

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Mat Evans / University of Sheffield

A Roomba robot outfitted with whiskers and reprogrammed with monkey smarts determines what type of flooring is beneath it.

The next time you find yourself trapped under a pile of rubble, your savior might be a Roomba — souped-up with whiskers and a monkey brain.

Such a robot was recently shown to outperform other whiskered robots in characterizing its environment, using technology that could wend its way into next-generation search and rescue robots, the University of Sheffiled reports.

Researchers have long known that rats sense their environment with whiskers. But models of how their brains interpret these signals vary. 

One approach, for example, has assumed that rats looked at whisker movement patterns and vibrations over a set period of time and then used that information to make a decision.

But various robots created with this model, Science Now explains, correctly guessed the floor beneath them only 50 to 80 percent of the time, after 0.4 seconds of exposure.

Nathan Lepora at the University of Sheffield in England wondered if outfitting these robots with a model of how the monkey brain makes decisions would be an improvement.

Previous research shows that individual neurons in monkey brains ramp up their firing rates when making decisions about the direction of motion for a group of random dots flashing on a screen.

A decision is made when the firing of these neurons cross a certain threshold. If the neurons responding to the up motion cross the threshold first, for example, the monkey would say the dots are moving up.

Lepora and his team fitted a brain model based on this monkey study into an existing Roomba with rat whiskers and found that it nearly flawlessly correctly identified the type of flooring beneath it.

The findings are reported Jan. 25 in the Journal of the Royal Society Interface.

In addition to improved rescue robots, the result suggests that rat brains may function similar to those of monkeys — in fact, they "suggest the possibility of a common account of decision-making across mammalian species," the team conclude.

[Via: Science Now and University of Sheffield]

More on whiskers, rats, monkeys, and brains:

• Virtual whiskers have the touch
• RatCar takes to the robo-road
• 3-D model of rat brain circuit created
• Cat brain inspires computers of the future
• How whiskers help rats find their way